Various hybrid powertrain architectures are known for managing the input and output torques of various prime-movers in hybrid vehicles, most commonly internal combustion engines and electric machines. Series hybrid architectures are generally characterized by an internal combustion engine driving an electric generator which in turn provides electrical power to an electric drivetrain and to a battery pack. The internal combustion engine in a series hybrid is not directly mechanically coupled to the drivetrain. The electric generator may also operate in a motoring mode to provide a starting function to the internal combustion engine, and the electric drivetrain may recapture vehicle braking energy by also operating in a generator mode to recharge the battery pack. Parallel hybrid architectures are generally characterized by an internal combustion engine and an electric motor which both have a direct mechanical coupling to the drivetrain. The drivetrain conventionally includes a shifting transmission to provide the preferable gear ratios for wide range operation.
One hybrid powertrain architecture comprises a two-mode, compound-split, electro-mechanical transmission which utilizes an input member for receiving power from a prime mover power source and an output member for delivering power from the transmission, typically to a vehicle driveline. The prime mover power source typically comprises an internal combustion engine. Motive torque is transmitted to the transmission from first and second electrical machines operatively connected to an energy storage device for interchanging electrical power therebetween. A control unit is provided for regulating the electrical power interchange between the energy storage device and the electrical machines.
There is a need for a hybrid powertrain control system having a control architecture that is operable to select an optimal operating mode and optimal operating point, and operable to control operation of the powertrain system.